High-frequency power-limited lighting system

Abstract

A lighting system for a suspended ceiling comprises a central high-frequency power source feeding a plurality of power conditioning units permanently wired-in and mounted in various locations on the permanent ceiling above the suspended ceiling. Each such power conditioning unit provides a power-limited Class-3 high-frequency voltage at an output receptacle and is operable to power a special fluorescent lighting fixture by way of a light-weight flexible two-wire detachable connect cord. Special fluorescent lighting fixtures are mounted in the suspended ceiling, with each such lighting fixture being powered from a power conditioning unit mounted somewhere nearby on the permanent ceiling above. Due to the Class-3 power-limited nature of the output of each of the power conditioning units, as combined with the detachable light-weight and flexible nature of the connect cords, each individual lighting fixture may be treated as a plug-in portable lighting product; which implies a particularly high degree of flexibility in installation and use. As a consequence of the high-frequency operation, the size and weight of the impedance matching means required in the special lighting fixture (to provide proper operation of the fluorescent lamp means therein) is very modest, which results in a particularly compact and light-of-weight lighting fixture.

What is claimed is: 
     
       1. A lighting system comprising: frequency conversion and distribution means connected with an ordinary electric utility power line and adapted to generate and distribute a substantially non-current-limited relatively high frequency voltage to a set of non-power-limited terminals at each of a plurality of different locations, whereby each set of non-power-limited terminals is provided with said non-current-limited voltage;   a plurality of power conditioning units, each power conditioning unit: (a) being electrically connected with the set of non-power-limited terminals at one of said locations, (b) having current-limiting means operative to transform the substantially non-current-limited voltage received therefrom into a manifestly current-limited output voltage, and (c) having a pair of output terminals across which said current-limited output voltage is provided; and   a plurality of lighting fixtures, each such lighting fixture: (a) having a pair of input terminals, (b) having lamp means, (c) having connect and matching means operative to connect between the input terminals and the lamp means, and to match electric power provided at the input terminals to the electrical requirements of the lamp means, (d) being adapted, by way of said input terminals, to be powered from a manifestly current-limited relatively high frequency voltage such as said output voltage, and (e) being disconnectably connected, by way of said input terminals, with the output terminals of one of said power conditioning units;   whereby each lighting fixture is disconnectably connectable with the output terminals of one of said power conditioner units and operable to be properly powered by the current-limited output voltage provided therefrom.   
     
     
       2. The lighting system of claim 1 wherein the maximum power output available from said non-power-limited terminals is of a magnitude that is regarded by an authoritative entity, such as the NATIONAL FIRE PROTECTION ASSOCIATION, as being potentially unsafe from a fire initiation viewpoint, while the maximum power output available from the output terminals of each of said power conditioning units is limited to a magnitude that is regarded by said authoritative entity as being acceptably safe from a fire- initiation viewpoint. 
     
     
       3. The lighting system of claim 1 wherein the maximum power output available from said non-power-limited terminals is substantially higher than 250 Volt-Ampere, while the maximum power output available from the output terminals of each of said power conditioning units is on the order of 250 Volt-Ampere or less. 
     
     
       4. The lighting system of claim 1 wherein the electrical output characteristics of each of said power conditioning units conform to the specifications for Class-3 circuits as defined in Article 725 of the 1984 National Electrical Code. 
     
     
       5. The lighting system of claim 1 and a plurality of flexible electrical cord means, each such cord means being operable to provide connection between the output terminals of one of said power conditioning units and the input terminals of one of said lighting fixtures, thereby permitting each fixture to be installed and operated at a location remote from the power conditioning unit from which it receives its power. 
     
     
       6. The lighting system of claim 5 adapted for use with a suspended ceiling that is located underneath and suspended from a permanent ceiling, wherein said power conditioning units are permanently mounted onto said permanent ceiling and wherein said lighting fixtures are non-permanently mounted in said suspended ceiling. 
     
     
       7. The lighting system of claim 1 wherein at least one of said lighting fixtures comprises a fluorescent lamp. 
     
     
       8. The lighting system of claim 7 wherein said fluorescent lamp is ballasted by one of said power conditioning units. 
     
     
       9. The lighting system of claim 7 wherein an electrical cord means requires no more than two electrical conductors for proper operation of said fluorescent lamp. 
     
     
       10. A fluorescent lighting system for a suspended ceiling, said suspended ceiling having a grid-structure and being suspended some distance underneath a permanent ceiling, said lighting system comprising: frequency converter means connected with an ordinary electric utility power line and operable to provide a substantially non-current-limited relatively high frequency primary voltage at a set of primary output terminals;   distribution means connected with said set of primary output terminals and operable to distribute said primary voltage to each of a number of pairs of secondary output terminals positioned at different locations on said permanent ceiling, each of said pairs of secondary output terminals providing a substantially non-current-limited relatively high frequency secondary voltage;   a number of power conditioning units, each power conditioning unit: (a) being permanently mounted at one of said locations, (b) being electrically connected with a pair of secondary output terminals at that location, (c) having currentlimiting means operative to transform the substantially non-current-limited relatively high frequency secondary voltage received therefrom into a manifestly current-limited relatively high frequency tertiary voltage, and (d) having a pair of tertiary output terminals across which said current-limited tertiary voltage is provided; and   a number of fluorescent lighting fixtures, each lighting fixture: (a) being non-permanently mounted in the grid-structure of the suspended ceiling, (b) having a pair of input terminals, (c) having lamps means, (d) having connect and matching means operative to connect between the input terminals and the lamp means, and to match electric power provided at the input terminals to the electrical requirements of the lamp means, (e) being adapted to be properly operated from a voltage such as said manifestly current-limited relatively high frequency tertiary voltage, and (f) being disconnectably connected with the tertiary output terminals of one of said power conditioning units by way of a flexible electrical cord means;   whereby each lighting fixture is disconnectably connectable with the output terminals of one of said power conditioner units and operable to be properly powered by the current-limited voltage provided therefrom.   
     
     
       11. The lighting system of claim 10 wherein the rate of energy output potentially available directly from one of said pairs of secondary output terminals is considered by an authritative entity, such as the NATIONAL FIRE PROTECTION ASSOCIATION, as being non-safe from a fire initiation viewpoint, whereas the rate of energy output potentially available from a pair of said tertiary output terminals is considered by said authoritative entity as being reasonably safe from a fire initiation viewpoint. 
     
     
       12. The lighting system of claim 10 wherein at least one of said fluorescent lighting fixtures comprises a replaceable fluorescent lamp. 
     
     
       13. The lighting system of claim 10 wherein at least one of said fluorescent lighting fixtures comprises a fluorescent lamp requiring for its proper operation a manifest currentlimiting function, and wherein said manifest current-limiting function is provided by the power conditioning unit to which this one fluorescent lighting fixture is connected. 
     
     
       14. A lighting system adapted to be powered from the power-line voltage on an ordinary electric utility power line and comprising: frequency conversion means connected with said power line and operable to provide an output of substantially non-current-limited relatively high frequency primary voltage;   distribution means connected with said primary voltage and operable to provide a substantially non-current-limited relatively high frequency secondary voltage across a pair of secondary output terminals at each of a number of different locations;   a number of power-limiting means, each connected with a pair of secondary output terminals and each providing across a pair of tertiary output terminals a voltage that is: (a) manifestly current-limited such that the maximum Volt-Ampere product extractable from said pair of tertiary output terminals is limited to a magnitude that is considered by an authoritative entity, such as the NATIONAL FIRE PROTECTION ASSOCIATION, as being reasonably safe from fire-initiation hazard; and   a number of lighting fixtures, each lighting fixture: (a) having a pair of input terminals, (b) having lamp means, (c) having connect and matching means operative to connect between the input terminals and the lamp means, and to match electric power provided at the input terminals to the electrical requirements of the lamp means, (d) being adapted to be properly operated from the voltage available from said pair of tertiary output terminals, and f) being connectable with said pair of tertiary output terminals by way of a disconnectable two-conductor electrical cord means;   whereby each lighting fixture is disconnectably connectable with the tertiary output terminals of one of said power-limiting means and operable to be properly powered by the current-limited voltage provided therefrom.   
     
     
       15. The lighting system of claim 14 wherein the magnitude of the power available from said pair of power-line terminals is considered by said authoritative body as being potentially unsafe from a fire initiation viewpoint. 
     
     
       16. A lighting system adapted to be powered from the relatively low frequency voltage on an ordinary electric utility power line, said system comprising: frequency conversion means connected with said power line and operable to provide a substantially non-current-limited relatively high frequency output voltage at a set of distribution conductors;   a plurality of lighting fixtures non-permanently mounted at different locations at or near a mounting surface, each lighting fixture: (a) having a set of input terminals, (b) having lamp means, (c) having connect and matching means operative to connect between the input terminals and the lamp means, and to match electric power provided at the input terminals to the electrical requirements of the lamp means, and (d) requiring for proper operation that a relatively high frequency voltage be provided at its input terminals; and   for each lighting fixture:   (i) power conditioning means that is non-disconnectably connected with said distribution conductors and mounted at or near said mounting surface in a location within a relatively short distance from the lighting fixture, said power conditioning means being operable to provide at a set of output terminals the relatively high frequency voltage required by said lighting fixture, and   (ii) flexible cord means operable to provide disconnectable electrical connection between the input terminals of said lighting fixture and the output terminals of said power conditioning means;   whereby each lighting fixture is disconnectably connectable with the output terminals of one of the power conditioning means and operable to be properly powered by the high frequency voltage provided therefrom.   
     
     
       17. The lighting system of claim 16 wherein the maximum power output available from said set of distribution conductors is of a magnitude that is regarded by an authoritative entity, such as the NATIONAL FIRE PROTECTION ASSOCIATION, as being potentially hazardous from a fire initiation viewpoint, while the maximum power output available from the output terminals of said power conditioning means is limited to a magnitude that is regarded by said authoritative entity as being substantially non-hazardous from a fire initiation viewpoint. 
     
     
       18. The lighting system of claim 16 wherein the maximum power output available from said set of distribution conductors in substantially higher than 250 Volt-Ampere, while the maximum power output available from the output terminals of said power conditioning means is on the order of 250 Volt-Ampere or less. 
     
     
       19. The lighting system of claim 16 wherein the electrical output characteristics of said power conditioning means conform to the specifications for Class-3 circuits as defined in Article 725 of the 1984 National Electrical Code. 
     
     
       20. A lighting system for a suspended ceiling, said lighting system being adapted to be powered from the relatively low frequency voltage on an ordinary electric utility power line, said suspended ceiling having a grid-structure and being suspended some distance underneath a permanent ceiling, said lighting system comprising: frequency conversion means connected with said power line and operable to provide a substantially non-current-limited relatively high frequency output at a set of distribution conductors;   a plurality of lighting fixtures non-permanently mounted at different locations in said grid structure, each lighting fixture: (a) having a set of input terminals, (b) having lamp means, (c) having connect and matching means operative to connect between the input terminals and the lamp means, and to match electric power provided at the input terminals to the electrical requirements of the lamp means, and (d) requiring for proper operation that a relatively high frequency voltage be provided at its input terminals; and   for each lighting fixture:   (i) power conditioning means that is non-disconnectably connected with said distribution conductors and mounted at said permanent ceiling in a location approximately above and within a relatively short distance from the lighting fixture, said power conditioning means being operable to provide at a set of output terminals the relatively high frequency voltage required by said lighting fixture, and   (ii) flexible cord means operable to provide disconnectable electrical connection between the input terminals of said lighting fixture and the output terminals of said power conditioning means;   whereby each lighting fixture is disconnectably connectable with the output terminals of one of the power conditioning means and operable to be properly powered by the high frequency voltage provided therefrom.